12561338881 has 48 divisors (see below), whose sum is σ = 16409331840. Its totient is φ = 9389053440.

The previous prime is 12561338821. The next prime is 12561338903. The reversal of 12561338881 is 18883316521.

It is not a de Polignac number, because 12561338881 - 2⁷ = 12561338753 is a prime.

It is a super-2 number, since 2×12561338881² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (12561338821) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 12159541 + ... + 12160573.

It is an arithmetic number, because the mean of its divisors is an integer number (341861080).

Almost surely, 2^12561338881 is an apocalyptic number.

It is an amenable number.

12561338881 is a deficient number, since it is larger than the sum of its proper divisors (3847992959).

12561338881 is a wasteful number, since it uses less digits than its factorization.

12561338881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1626 (or 1613 counting only the distinct ones).

The product of its digits is 276480, while the sum is 46.

The spelling of 12561338881 in words is "twelve billion, five hundred sixty-one million, three hundred thirty-eight thousand, eight hundred eighty-one".